The present invention relates to a magnetic filter adapted to be mounted in a gear box or the like for absorbing magnetic metal powder such as iron powder or the like contained in oil within the gear box.
Heretofore, magnetic filters of this type were formed as shown schematically in FIG. 10, in which a permanent magnet piece (b) was fitted in a box-shaped magnetically permeable plate (a) in such a manner that the front surface of the permanent magnet piece was on the same plane as the opening plane of the box-shaped magnetically permeable plate (a), and the magnetically permeable plate (a) was mounted on an inner wall surface (c) (see FIG. 12) of a gear box or the like to attract or adsorb magnetic metal powder such as iron powder or the like mixed in the oil within the gear box.
The above-mentioned magnetic filter in the prior art had shortcomings such as if adsorbed iron powder (d) approached the saturated adsorption amount vibration or the like was present, the iron powder would be disengaged from the filter and would be dispsered into a region outside of the magnetically permeable plate (a) where the magnetic force is not exerted (See FIG. 11). Also, as the magnetic field (e) extends greatly outside of the magnetic filter beyond the open end portion of the magnetically permeable plate (a), the gear box is apt to be magnetized (See FIG. 12).